Interpolating receiving system



Feb. Z6, 1935. w. A. KNooP INTEROLATING RECEIVING SYSTEM 2 Sheets-Sheet1 Filed May 13' 1929 AA VVV mmmmmmmnmmmmmmm Ff ik @y ab' @y dv Il Il n nJig-H Feb. 26, 1935. w A KNQQP 1,992,220

INTERPOLATING RECEIVING SYSTEM I Filed Mayl, 1929 2 Sheets-Sheet 2 miiF/G. 3

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i s arl l l? l Z5 /M/EN 70H W I4. KNooP A TmR/vfy l Patented Feb. 26,1935 UNITEDN STATESV PATENT"ortica"; y Y A l1,992,229 Y 'u i 'l iINTERPoLA'rING RECEIVNG SYSTEM A William A. Knoop, HempsteacLN;`Y.,assignor to Bell Telephone Laboratories, Incorporated, New York, N.Y., a corporation of New York` Application May 13, 1929, serial No.scarsi y Y 41 Claims. (Cl. 178-7-88) This invention relates to highspeed synchron-` This expression is somewhat misdeseriptive ofthe systemof this invention (because short impulses are rebuilt without vibrationof any relay i and therefore, in this Yspecification the expressioninterpolating receiving system will be used to deiine a system whichrestores, or interpolates short signal impulses Which have beenattenuated to mitting the impulses into the next line section. As thespeed of transmission over a submarine cable or a long transmission lineis increased -the single impulses `of dot length, whether positive ornegative polarity, often become so attenuated, that is so reduced inv:strength and distorted or altered in wave shape form by thetransmitting medium, that With the customary voltages applied, perfectreceptionat high speed is difcult. This condition also exists in signalsof a length greater than the single or dot impulse in that the beginningof theimpulse is attenuated so that theiirst part of the signal whichcorresponds to the nrst part of the combination is not correctlyreceived. The eiect of such distortion and loss of energy isconsiderably minimized'by the use of the Grul-H stad relay whichcomprises a three winding polarized relay. The usual Gulstad relay isprovided With a line Winding, `an opposing winding, and an acceleratingwinding', the latter two being locally operated. By proper local circuitarrangements, including condensers and resistances, the 40 currentflowing through one of the local windings operates the relay armature toits opposite contact, which thereupon closes "a circuit sothat currentof reverse polarity iiows through the winding and the armature is movedback toits original position. If the armature vibrates between itscontacts in synohronism with the transmission of the signals, the effecton the local apparatus is the same as if impulses of periodicallyreversed polarity were being received. In this manner at- 50 tenuatedimpulses, although too Weak to operate the line relay armature, are notlost. By adjusting the resistances and condensers in the local circuits,the relay tongue can be arranged to vibrate between its armaturecontacts at lany desired frequency. However, considerable d ifliculty lsuch an extent that they are incapable oi coni trolling a receivingrelay or; a relay `for retrans-A -1 is experienced withthis relaysystemndue tothe fact that no means-is provided for insuring absolutesynchronism between thevvibration of the armature and thereceivedsignalingimpulses.` K

Considerable diicultyis also experienced dueto the fact that thevibration causes continuousv Wear of thearmaturecontacts. f

Attempts to overcome the-diiculties ,disclosed `of January 6,1925.` Inthese'two patents, distributors` aredisclosed which rotate at the properspeedfor maintaining Vthe vibration of the armature of the relayoperating asa Gulstad relay in synchronism with the received impulses.The resistances,andcondensers of the Gulstad system are replacedvpartially by `distributors which control the speedof relay operation'.Here again,

' however, the armature of the relay vibrates continually and there istherefore the same drawbackof` wear on the armature. 3 Y l The presentinvention `provides arrangements for operatingV velectro-responsivedevices of `the Gulstad relay ,type-in such-a manner that there` isnormally no Wear on the armature part Vand the operation isautomatically maintained Vin synchronism with the signal impulses.

`This invention also provides for operating elec--y Another object ofthisinvention isto provide means for repeating attenuated signalingimpulses by electromagnetic means arranged in such circuits that theirarmaturesdo not vibrate While signals are not being received. 1 f

IStill another object of this inventionV isto provide means whereby theprinter selecting magnets maybe energized to operate them for a greaterpercentageof Vthe signal period than could normally be obtained underthe Gulstad relay system. A il `I-Ieretoforey as noted above, ithas beena practice to rebuild or restore short impulses at `the receivingstationby means of `relay systems in which a relay vibrates under the controlof-,special `distributor segments to automatically restore signalimpulses of unit length. Such: vibrating relay systemshave ratherdefinite `speed limitan ac tionsand long loaded telegraph cables are nowin existence which have a possible speed of transmission exceeding thatat which they are capable of operating satisfactorily.

The present invention'is exemplified by an embodiment in lwhich athree-position line relay or mixing relay -controls the impulses whichtwo halving relays, each controlling the other, transmit to each other,in accordance withline impulses whereby line impulses acting through theline or mixing relay cause` the two relays to transmit to the printermagnets orretransmitting relays impulses coming in from the line. Whenthe line relay is uncontrolled by incoming impulses and stands in itsmid-position the two halving relays each assumesY opposite positions andrelay to the printer. magnets or retransmitting relays properly timedand phased unit impulses. 4 y, Fig. 1 is acircuit diagram, withdeveloped distributors, of a circuit inV accordance with the invention;f

Fig'. 2A is a series of graphs explanatory of the operative actionof theparts of Fig. 1;

f' Fig. 3 is a circuit diagram of a modiiied form using. asingleprintermagnet; and.

Fig. 4 is a circuit diagram of'a further modied circuit.` f

DescriptionY f circuit. of Fig. 1

A cable .10 is'connected to a transmitter transmitting impulses at suchhigh speeds that. the unit length impulses do notsarrive at Vthereceiver in operative amplitude. Amplifier 11 typies any suitableamplier. of `thereceived''impulses and has its output-circuit connectedto relay LR Vwhich isa line or mixing relay.. Shaping networks ofthe'type ordinarily employed will be used, in practice but are notshown. f

Relay LR isa three-position line relay whose armature remains in acentral position on of both of its contacts whenv no signal impulses ofeffective amplitude are being received. its right hand? contact isconnected to-positive battery and its. lefthand contact'to negativebattery. Its armature isconnected by a resistance r' to point 14 on apotentiometer resistance 1' which isV dividedV intoV fourl parts bypoints 12, 13.ar1dV 14, Whiclrmay be adjustable. Point 141s adjustablyconnected along' the middle section of potentiometer r. -When thearmature of relay LR isl in its middle position point 13is negative withrespect to point 14 and point 12'is positivewith respect to point 14.When-the'armatureis to the left, point I4 isnegative with respect topoint 13; when the armature is to the right, point 14' is positive withrespect to Apoint. 12.

RelaysV R1- and PR1 in parallel are controlled bytwovcircuits extending'from either of points 12 or '1231 through the right or. left handcontacts of relay R2, Segments la, conductive brush 1'5, ring 16 andconductor 17, to point 14.

,RelaysRz and PRz in parallel are controlled by two circuits extendingfrom either points 12 or 133 through the right or left hand contacts'oi'relay R1, conductive brush 15',V segments 2d, ring 16', and conductor 17to point 14.V Y

Alternate printer magnets of a channel suchl as magnets 1,y 2, 3,14, 5are connected' to separate sets of distributor-'segments 18 and-19, eachset of segments being connected by a brush to a corresponding'ring oflong segments, ring 20 being thelong segments for short segments 18, and.ring 21 being the long segments-for short segments 19.V Dead segmentsare located between the live segments 18V and 19. The dead segments maybe considerably shorter than a unit impulse and the live segmentsconsiderably longer thereby permitting the transmission, to therelatively slowacting printer magnets, of a Vrelatively long impulse,without the use of pulse lengthening Vtubes or other devices. In otherwords, the segments 18 and i9Y are longer than the distance from thecenter of a segment 1a to the center of a next adjacent segmentV 2a. Theimpulses transmitted to the printer magnets may be made anx/'length fromshorter to longer than al unit impulse by making the live segments cisuitable length. To indicate a ve channelrsystem the printer magnets ofchannel #l are designated 1, 2, 3, 4, 5, of channel #2, 1I, 21, 31, 4I,5I, etc., up to 51V.

Fig. 2 discloses in curve 30 a train of transmitted impulses, in curve40 a corresponding train Y Y of received impulses,V in curve 5G thecorrespondingly proper movements of relay R1, in curve 60 thecorrespondingly proper movements of relayV When noisignals or"controlling amplitude are The time of transmission Y Varriving relayLRstands in its central position.` and relays R1 and R2 standstill onopposite con'-V tacts and arernaintained cri-opposite contacts each 1 bythe otherq-Relays PR1 and PE2 follow the corl responding relays R1 andR2 and likewise stand still on opposite contacts. The circuit `forcontrolling relays R1 andPRl isl from point 12, of

vpositivepolarity, through right Contact of relay R2, windings of. R1and PE1 in parallel from right to left, segments 1a., brush 15, ring 16and conductor 17 to point 14. The circuit for controlling i relays R2and PR2 is from point 13, of negative polarity, through left contact ofrelay R1, Windings of relaysRz and PRz in parallel from left to right,segments 2a, ring 16, and conductorV 17 to point 14.

Let it be supposed that a long positive impulse is sent from thetransmitter beginning at time c.

lay LR is released and returns its armature to its central position.vPoint 13 then again becomes negative with respect to point 14 and sincepoint i3 is connected to theleft hand contact of relay R2, upon whichits armature is now resting, a circuit Vis closed from point 13, leftcontact of R2, and windings of relays R1 andPRi in parallel, a segment2a, ring i6, and conductor 17 to point 14. The negative current throughwindings of relays R; and PR1 causes them to move their armatures to theright, whereupon R1 and Rz-again stand in opposite positions andregenerate alternate positive and negative limpulses until the linerelay LR is again operated, which will happen, in the case illustratedby Fig. 2 at about time h. From curves 3G, 40, 50, 60 and 70 theoperation of the system for other combinations-oi long and shorttransmitted impulsescan readily be traced; VV'I'he `printer magnetsaredivided Ainto `two VIt will be noted that after any long impulse`such .as occurs at time `c to e or g to the relays R1, R2 are sopositioned that the subsequent impulse or impulses of unit length to beregenerated are always incorrect order. 1

It will be noted that the relays R1 and R2, to-` gether with the relaysPR1 and PRa comprise electromagnetic means'provided with armatures forrelaying impulses received from the' transmission line 10 to thereceiving printer magnets 1, 2, 3, etc. The relays'R1 and R2 each isconnected to control the `other by means of circuit arrangements whichmaintain the armatures of said relays in` engagement with apredetermined contact when no impulses are being received over the linein effective amplitude." The predetermined contact uponv which theserelays R1 and R2 stand is determined by the sign of thelong impulse, ofAtwo or more unitsV duration4 last received. When the relays R1 andRaremain in xed position the impulses relayed to the printer magnets areof alternate polarity.A The distributor rings 16, together with segments1a, 2a, etc., constitute one distributor; the rings 18, constituteanother distributor; and the rings 19, 21 another distributor. The lasttwofnamedmay be arranged ina single rowas shown in Fig. 4 orin two rowsas-shown in Fig. 1. The two-row `arrangenfient `has the advantage thatthe live segments to the printer magnets may be over 100% or" the timeduration of a unitsignaling impulse as transmitted, thereby y'insuringthat the printer magnets will be energized by an impulse of properpolarity for the full time during which the relays PR1 and PR2 maintaintheir armatures upon `any given contact. There is no physical limitationupon therelationship of the distributors controlling the relays R1, R2,and those controlling the printer magnets except that they besynchronized and adjusted toi suitable phase relation.

Description Vand operation of circuit of Fig. 3

This circuit is a modified form of that of Fig.

1 and uses a singleprinting relay. The corre- Y spending` parts of Fig.1 are in light lines and identiiedV by corresponding characters. Themodified velements are designated by heavy lines and comprise a printerrelay PR1,2 which isconnested between the armature of relay LR. and theringld.` Conductor 17 of Fig. 1 is omitted from Fig. 3. Relay PR1,2follows the movements of each signal impulse whether locally regener`ated or incoming to the three-elementline relay LR. Relay PR1,2 controlsthe printer magnets 1, 2, 3 .1 51V, etc., to select or not in accordancewith the impulse transmitted over the line.`

Description of circuit of Fig. 4 Fig. 4 is a further modified circuit.The re' lays LR, R1, R2, PR1and PR?. of Fig. 4 are generor" relays R1and R2 are veach connected to batteryv through 500 ohm resistances. Thegeneral relation between the values of the 500 ohm and the 250 ohmresistances is essential for operation although these exact values areunnecessary.

groups, alternate magnets belonging to a group.

`All magnets of both groups are connected toa common ring 24 by brush25' which sweeps over lSegments 25 connected tothe several. printermagnets 1, 2, 3, 4, 5, 1I etc., up to 5W, in a five channelsystem,although any reasonable number of channels either even or odd may beemployed. For reversing the impulses to opposite channels, the ring 24may be split at the `end of each` channel and the-alternate channelllength segmentsconnected to positive and negative battery respectively.Battery on the armatures of relays PR1 and PRZ may then be replaced byground. 1 Y

Operation ofcircuit of Fig. 4 When the line relay stands in neutralposition,

as when no linesignals of controlling amplitudel are arriving, relays R1and Rz'eachholds the other in opposite positions and also hold relaysPRi andrPRz in opposite positions. The printer magnets will receiveimpulses of positivefand zero polarity alternately thereby correctlyreproducing the regenerated impulses. When long impulses control theline relay LR the one of relays R1 and R2 corresponding to the unit timevduring which the relay LR'becomes operated is operated. This transmitscorrespondingly long impulses to the printer magnets. The cycle ofoperations indicatedin Fig. 2 is equally applicable to Fig. 4.

Two features of operation require mention. When the relay LR operates, apulse is delivered to the controlled magnet R1 or Rz stronger than thatdelivered when they merely hold each other in opposite position.Likewise when relay LR fallsback to neutral position and relays R1 `andR2 are on the same contact the next pulse delivered to move one of themis extra strong. The occurrence of these extra strong impulses at theproper times to move the relays With'the occurrence of 'weaker impulseswhen they merely are to be held in position is a desirablefeature of thesystem.

What is claimed is: 1. Ina receiver of a synchronous distributor impulsetransmission system of the type in which unit length impulses areregenerated and plural unit length impulses are transmitted,` electro- Ymagnetic means directly controlled by the receivedimpulses incombination with al plurality of relays functioning to regenerate andrelay to a set of distributor segments unit length impulses whenstanding still uncontrolled by said electromagnetic means and to relayto said set of distributor segmentsplural unit impulses when controlledby said'electromagnetic means.

2. In a system in accordance with claim 1, a

pulse lengthening arrangement comprised in that the set of distributorsegments are'divided into' a plurality of serieswhereby a live segmentof said set may be not less Vthen 100% of the length corresponding to aunit` impulse. 1

normally stand still to regenerate unit impulses during the time saidregenerative relays are uncontrolled by said'line relay means.

4. A system in accordance with` claim 3 in which the lineelectromagnetic means is a threepositionrelay..

5. A system in accordance with claim 3 in which said regeneratingrelaysV each controls the other .through a circuit extending through adistributor and connectedv to contacts of said line relay means' to beunder the control of said line relaymeans.

6. In a synchronous telegraph system, an interpolating receiving circuitcharacterized in this that is comprises a plurality ofrelaysindividually yconnected ,with a corresponding plurality of printerrings'on Vthe receiving distributor whereby the. regeneration of unitimpulses of alternately opposite polarity may be effected withoutmovement of the relay armatures.

'7. In a synchronous telegraph system comprising-.a rotary distributor,an interpolating circuit characterized in this, that a plurality oirelays are individually connected with a corresponding plurality .ofprinter rings on the distributor, and

aplurality of. groups of segments for relaying alternate positive andnegative impulses whenever said relays remain quiescent as the result ofthe reception of insumicent line current to actuate 8. .In a synchronoustelegraph system compris- Y ing a rotary distributonan interpolatingcircuit characterized this, that a plurality of relays are individuallyconnected with a corresponding plurality oiprinterrings on thedistributor, a plurality of groups ofrsegrnents for relaying alternatepositive and negative impulses whe-never said relays remain quiescent asthe result of reception of insucient line current toV actuate them, and

`connections whereby two successive segments (one each vfrom two of saidgroups) transmit on impulses of the same polarity whenever one of saidrelays is actuated from one position to another by an incoming impulseof line current.

9. In a' synchronous telegraph receiving system, a plurality ofrepeating devices adapted to supply positive and negative impulses,synchronlous vswitching means for distributing received signal impulsesto said repeating devices inV rotation and for concurrently applying toeach repeatingY device an impulse from the preceding device or" suchpolarity as to tend to operate said device to a position ropposite thatoi the'preceding device, signal recording means, and synchronousswitching means for distributing lm- ,pulsesY repeated by said repeatingdevices to said signal recording means.

1Q. In a synchronous telegraph receivingr sysf tem, a plurality oirelays each having an operating winding means and an armature operablebetween contacts connected to opposite poles of source of potential,synchronous distributing means for distributing received signal impulsesto the winding means of each relay in rotation andl reversed polarity tosaid magnets, a distributor, means including said distributor foroperating',

Vthe armatures of said electromagneticA means,

each electromagnetic means beingv under the control of the other, andmeans independent of said rdistributor for operating said.armatures ofsaid electromagnetic means in responsey to impulses received over acable or signaling line.

l2. In a telegraph system.,` a cable or signaling line over whichsignalingiimpulsesare attenuated, a plurality of receiving magnets,electromagnetic means, adistributor, means including saidelectromagnetic means and said distributor for operating said printermagnets in accordance with the operation of said electromagnetic means,

tures,` printing magnets, meansV including theY armatures of saidelectromagnetic means for operating said Vprinting magnets in accordancewith the signals transmitted oversaid signaling line,

said meansincluding a distributor, and means together with saiddistributor whereby the armatures of the electromagnetic means move onlyin response tothe received impulses.V

14. In a telegraph system,V a, signaling line, means transmitting codecombinations'of impulses over sai-d signaling line, means whereby onlyVcertain of said impulses are received, a distributor, andelectromagnetic means including armatures therefor for relayingall ofthe impulses transmittedover said signaling line to said distributor,said electromagnetic means operative to move its armatures only inresponse to impulses actually received.

15. In a signaling system, Va transmission line, means for transmittingimpulses overrsaid transmission line, printer receiving magnets, avdistributor, second means together with said distributor fortransmitting impulses of reverse polarity tovsaid printer receivingmagnets, while maintaining said second mean-sin iixed position, andmeans independent of said distributor for operating said secondmentioned means in response to received impulses.

16. In a signaling system, a signaling line over which the impulses sentare so attenuated that the rst portion of each4 impulse is not receivedat the receiving end, printer receiving magnets, a distributor, meanstogether with said distributor for operating said printer magnets inaccordance with said received impulses, said means being maintainednormally non-operative duringl the transmission of dash signals whilerepeating said dash impulses to said printer receiving magnets.

17. In a telegraph system, l printer receivingy magnets, electromagneticmeans for transmitting impulses of reversed polarity to said printermagnets periodically,4 a distributor, means to-l gether with saiddistributor whereby said electromagnetic means controls the operation oiif are so attenuated` that the dot impulses are not received, aplurality `of printerlnagnets, a first and a second electromagneticmeans, eachV of toV tributor, means for operating said electromagneticmeans in response to impulses receivedover said signaling line,` saidmeans being independent of said distributor, and means for operatingsaid Yprinter magnets, under control of said elecf tromagnetic means,said means including said distributors.

19. Ina-signaling system, a signaling line over` which` impulsestransmitted are` so attenuated that the impulses of dot character arenotfully received, a plurality of printer magnets, a nrst and a secondelectromagnetic means, a distributor, means .including said distributorfor operating each of said electromagnetic means under control of theother, means including said distributor for operating said receivingmagnets under the control of said electromagnetic means,

said printer magnet, beingoperat'edV inaccord'-` ance with `the impulsestransmitted over said signaling line, and means for operating said,A

electromagnetic means only in accordance' with the impulses receivedover said signaling line.

20.` In a telegraph system, the combination atV` a terminal station or`a repeating station, of an incoming signaling line, electro-responsivedevices, a distributor, second means together ,with` said distributorfor transmitting impulses res verse polarity to said electro-responsivedevices,

while maintaining said `second means .inapre-` determined position, andmeans independent of l said distributor for operating said secondnientioned means in response to received signal impulses. 21. In asignaling system, over which the signaling impulses transmitted are soattenuated that the dot impulses are not received, printerj receivingmagnets and'electromagnetic means in cluding armatures therefor arrangedto-cperate said printer magnets in accordance with said signalingimpulses transmitted over said signaling line, said electromagneticmeans being arranged to hold their armatures in engagement with apredetermined fixed contact While operating said printer magnetsinresponse to the dot 7 pulses of periodic reversed polarity to saidprinter'` magnets, said means being maintained ina predetermined iixedposition while transmitting said` impulses of reversed polarity, andmeans for .operating said rst mentioned means in response to signalingimpulses transmitted over said signaling system. f

said transmission line, printer receiving magnets, means fortransmitting :impulses of reversed polarity to saidA printerV receivingmagnets while maintaining said means in `lixed position and means forloperating said first mentioned means in response to received impulses.

ceiving magnets, electromagnetic means including armatures therefor for`transmittinglim- `pulses of reversed polarity to said receiving magnets,said armatures being maintained in engagement with their -xed contactswhile transmitting said impulses andV means responsive to receivedimpulses for operating said armatures to their reversed position.

' 26. In a telegraph system, a signaling lineover A,25. `In a telegraphsystem,` a pluralityl of re-` which signaling impulses transmitted areso .attenuated` that the dot impulses are lost,receiving electromagneticmeans includingv armatures, printer magnets, means including thearmatures of said electromagnetic means, for operating said printermagnets in accordance with the signals transmitted over said signalingline, and means includingcircuit arrangements whereby the armatures ofsaid electromagnetic meansare moved` Y `ing all of the impulsestransmitted over said sig-` naling line, said electromagnetic meansbeing operative to move its armatures onlyin response to actuallyreceived impulses.

28. In a telegraph system over which signaling.-

impulses are so attenuated that they do not operate receiving apparatus,receiver relays, repeating, means for repeating impulses received oversaid line to said receiver relays, said means being normallynon-operative while impulses are attenuated, and means Vincludingcircuit arrangements whereby said first mentioned means repeats saidattenuated impulses to said receiver relays.

29. .Inv a telegraph system, the combination at a terminal station orarepeating station, ofan.

incoming transmission line, electro-responsive devices, means serving tosupply Vimpulses of `reversed polarity to said electro-responsivedevices while maintaining said means in a predetermined position. v

30. In a telegraphsystem, the combination at a terminal stationor arepeating station, of an incoming transmission line, a plurality ofelectro,- responsive devices, means for supplying impulses of periodicreversedV polarity to said electro-responsive devices,` said means beingmaintained in'a predetermined iixed position while transmitting saidimpulses Vof reversed polarity, and

` means for operating said iirst mentioned means in response tosignaling impulses vtransmitted over said line.

31. In a telegraph system, an incoming trans-.1l mission line, aplurality of receiving magnets, a

pair of relays having armatures ion transmitting impulses `of reversedpolarity to said receiving magnets, said armatures being maintained inengagement with their iixed contacts when transmitting said impulses,and means for transmitting signaling yimpulses received over said 1in aplurality of electro-responsive devices, electro- 24. In a signalingsystem, a transmission line,V means for transmitting signaling impulsesover l magnetic means provided with armatures for relaying impulsesreceived from said transmission line to said electro-responsive devices,means including circuit arrangements for maintaining the armatures ofysaid` electromagnetic means in engagement with a predetermined contactwhile no impulses are beingyreceived over said line,vand means includingthe armatures of said electro- A terpreting devices, distributor means;extending naling `impulse as transmitted.

magnetic means for periodically.reversing'the polarity of impulses tosaid electro-responsive devices while no'impulses are being receivedover said line. l Y

'33. (In an interpolating system, including, vin combination, ,areceiving circuit comprising a pair of relaysgrecording means, and`means dependent -upon the operation of Vone of said relays to supplyimpulses of more than unit length and render eiec'tive two or more ofsaid recording means.

V34. Ina telegraph System, the combination of a signaling .line overwhich the shortest unit signaling impulses transmitted arrive soattenuated as not to `be received in effective amplitude with ja relayinstrumentality connected to said line to be voperated in response tolonger receivedjsignaling impulses,.other relays, distributor meansV forextending a circuit of polarity determined by the existing position ofsaid relay instrumentality in succession tov saidirelays, signalimpulseincircuits from one or another oi said other relays to saidsignal impulse interpreting devices, and interconnections betweenv saidother relays controlling them in such manner that said interpretingdevices correctly interpret the shortest unit signaling impulses as Wellas the longer impulses. j

35. A system in accordance with claim E4, in which the circuit extendedby said relay instrumentality is operatively-continued by said relayinstrumentality for a time short as compared to Y the time duration ci afull unit signal impulse as transmitted. 'Y Y 36. A system inkaccordance with claim in which the circuitsextended to said impulseinterpreting devices are operatively controlled by said other relays fora time duratien which is long compared to the time duration of a fullunit sig- 37. A system in accordancewith claim 3d, in which the circuitsextended to said impulse interpreting devices include active distributorsegments of length corresponding to the time durationY of 100% of a fullunit signaling impulse as transmitted. v

f 38. A system in accordance with claim 34, in which the circuitsextended to said impulse interpreting devices include active distributorsegments f of length corresponding toa time duration far unit signalimpulse period While permitting the transmission or" impulses totheprinter magnets for any desired percentage of Vthe unit signal impulseperiod up t0 100 per cent.

40. n a telegraph system, theY combination of a terminal station or arepeating station, of an incoming transmission line, electro-responsivedevices, means serving to supply impulses of reversed poiarity to Ysaidelectro-responsive devices While maintaining said means in apredetermined position, distributor means for ,limiting Ythe effect ofline impulses upon said electro-responsive de- -ces to a time intervaloi short duration and ieans for vextending. on from saidelectro-respensiye devices operating impulses of duration greater thansaid time intervals of short duration; jai. A system in accordance withclaims() in which the means for extending on the `impulses is circuitinterrupting means for limiting the duration of the impulses.

, WILLIAM A. KNOOP.

